First of all, you need to define from which country you are looking for specialist. You can сheck the ratings of countries with the best IT-specialists, usually many countries which have made any progress in IT-sphere try to concentrate all their efforts on reinforcing this field. That's why even a middle specialist from countries with high-developed IT will have the equal level of education and experience as senior specialist from any other country.

How to choose good software developing company? What tips can you share?

I recommend you to check reviews on software development companies on Top10Devs website. They collect information about different companies and only real reviews from clients. For example take a look Fueled reviews they specializes in product promotion, design, and development.

I can say for sure, if you don't have enough time to develop your app/website, it's better to outsource this task. I was recently launching my business, I needed a powerful website to make my business more dynamic. I wanted a website that responded to my company’s motto – clean, clear, and concise. I turned to the guys from this company https://masterseo.ca/ , and they did their best to make it exactly I was looking for.